Hessler said the phenomenon of migrant workers, such as the experiences of his former students, helped inspire the book.

"It (the rise of migrant workers) is the most important social development in China over the past decade," he said. "It involves such a huge number of people.

"On the downside, it has seen some people live in really rough conditions or be cheated out of their wages by their bosses. But at the same time, there is an enormous number of positives, where people have been able to redefine and improve their lives."

The isolation sometimes felt by his former students as they head into unknown and almost alien cities is compounded by the fact they are, in a sense, pioneers. They have no historical frame of reference to guide them.

During one visit to his home village, Jefferson Foster wrote a letter to Hessler, published in the book, of how the place felt deserted.

"It makes me sad that I cannot find familiar people or friends who I knew well when I was young," wrote Jefferson Foster.

"Sometimes I think this kind of life, going out to small coastal regions without a stable home, is the saddest and the most stressful thing in the world."

He knew in his heart, he added, that he would never really return home.

Hessler said: "Most of the people who were in my class and this current generation were born when or just after Mao Zedong died in 1976, so in a very literal sense, they have grown up with these changes.

"Young people have much more freedom than they had in the past. They have more money and opportunities, but that, in turn, creates other pressures. It doesn't necessarily make life easier."

The book also strikes parallels between the lives of migrant workers and those of foreigners in China.

In one letter from Shenzhen, Emily sympathizes with Hessler's experiences of life away from home.

She writes she "cannot understand what the natives said their dialects are strange to us, because their tone and rhythm are so far different from ours."

Hessler revealed: "Many of my students migrated to find work, and many of them have written similar letters to me at some point.

"It reflects the diversity there is in the country, but it is a really important experience for them and their individuality. It can be hard and traumatic, but it's a positive experience."

He said that he hoped the book can provide more of a human perspective and understanding of China, something he thinks is needed, particularly in the United States.

"I actually think it would be a good thing for people in America to do something like the migrant workers have done, go abroad to a new place and be in a different environment with a different language," Hessler said.

"They would return and be able to see things from a different perspective."

(Oracle Bones is available at Beijing's Bookworm Cafe.)

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